J. Chem. Eng. Data 1999, 44, 1207-1211
1207
High-Pressure Phase Diagrams of Methane + 1,2,3,4-Tetrahydronaphthalene and Methane + 9,10-Dihydrophenanthrene Mixtures P. Tobaly* and P. Marteau Laboratoire d’Inge´nie´rie des Mate´riaux et des Hautes Pressions, CNRS, Institut Galile´e, 93430 Villetaneuse, France
V. Ruffier-Meray Institut Franc¸ ais du Pe´trole, 1 and 4 Avenue de Bois Pre´au, 92852 Rueil-Malmaison, France
Equilibrium data on the methane + 1,2,3,4-tetrahydronaphthalene (tetralin) mixture at (294, 323, 373, and 423) K and on the methane + 9,10-dihydrophenanthrene mixture at (423 and 463) K are reported. The data have been obtained with a high-pressure cell and an infrared absorption method previously described.
Introduction This work is part of a continuing effort to increase knowledge about thermodynamic properties of crude oils and natural gases. It is of major importance to be able to calculate thermodynamic behavior of crude oils at all conditions encountered during petroleum processing. Usually, equations of state are used to perform these calculations, and binary interaction parameters are used by these models to predict multicomponent properties. If group contribution methods are used to calculate properties of those complex mixtures, then specific parameters relative to the interactions between groups of the molecules are needed. Similarly, if molecular simulation is used, parameters of the potentials must take into account the interactions between different molecules or groups. To calculate these parameters, experimental data on binary mixtures are necessary. We have been involved for many years in the experimental determination of phase diagrams of binary mixtures. Data for methane + 1-methylnaphthalene (Marteau et al., 1996), methane + hexane and methane + benzene (Marteau et al., 1997), and methane + squalane and methane + hexatriacontane (Marteau et al., 1998) mixtures have been previously published. Two new binary mixtures have been investigated, methane + tetralin (1,2,3,4-tetrahydronaphthalene) and methane + 9,10-dihydrophenanthrene. Results are presented hereafter. Experimental Section Materials. The purity of methane was 99.9%. Tetralin was obtained fom Aldrich with a purity of 99%. The purity of 9,10-dihydrophenanthrene (from Lancaster) was only 97%. Two other suppliers offer material with a purity of 94 and 95%. The purification of 9,10-dihydrophenanthrene seems to be so difficult that it can be assumed that the remaining impurities must be of a very similar nature. All compounds were used as is without further purification. The apparatus and experimental procedure have been * To whom all correspondence should be addressed. E-mail: tobaly@ limhp.univ-paris 13.fr.
Figure 1. Concentration of tetralin as a function of pressure in the gas and liquid coexisting phases for the mixture tetralin + methane at four temperatures (9, 294 K; 4, 323 K; b, 373 K; 0, 423 K).
previously described (Marteau et al., 1996). Concentration measurements of each component in the gas and liquid phases have been obtained with an accuracy better than 1%, as mentioned in the preceding paper (Marteau et al., 1998). The concentration of methane which remains high enough in both phases is easily measured with this accuracy. As for the other molecule, its concentration may be very low in the gas phase. Therefore, concentration measurements in the gas phase at low pressure are not reported because of too-low infrared absorption by the solute. Although measurable absorption could be obtained by increasing the absorption path length, it has not been done since measurements in this pressure range can be easily obtained using more classical methods. The relative
10.1021/je990045j CCC: $18.00 © 1999 American Chemical Society Published on Web 10/28/1999
1208
Journal of Chemical and Engineering Data, Vol. 44, No. 6, 1999
Table 1. Vapor-Liquid Equilibrium Data for Tetraline + Methane at (294, 323, 373, and 423) K (C1 ) Tetralin Concentration; C2 ) Methane Concentration) gas phase P/MPa 1.0 2.1 4.2 8.3 12.2 16.0 18.2 28.4 38.4 48.4 57.0 57.6 70.0 5.2 5.2 10.0 10.0 17.5 22.3 22.4 22.4 30.3 40.4 50.5 60.7 5.1 10.4 17.6 20.3 24.5 31.2 41.4 3.1 6.1 10.2 20.5 31.1 36.3
C1/(mol‚L-1)
0.056 0.146 0.215 0.222 0.353
0.112 0.224 0.380
0.041 0.104 0.257
0.027 0.079 0.206 0.321
liquid phase
C2/(mol‚L-1)
C1/(mol‚L-1)
C2/(mol‚L-1)
gas phase P/MPa
5.770
T ) 294 K 0.289 80.1 0.437 90.2 0.806 99.9 1.323 110.2 1.770 119.4 2.099 129.8 2.126 136.2 2.909 140.1 3.656 140.3 4.322 140.3 4.891 141.2 141.4 5.721
14.110 15.526 16.511
6.975 6.967 6.814 6.829 6.572 6.463 6.464 6.457 6.251 6.003 5.748 5.509
T ) 323 K 0.724 70.6 0.773 70.9 1.315 70.9 1.336 80.6 2.136 80.8 2.578 90.8 2.559 91.3 2.591 100.8 3.364 103.8 4.246 103.8 5.106 103.9 6.028
7.864 9.702 11.937
6.675 6.503 6.254 6.160 6.039 5.824 5.440
T ) 373 K 0.624 50.9 1.234 60.0 2.064 65.0 2.327 69.1 2.864 73.6 3.587 76.2 4.815
3.007 5.855 8.383 9.526
6.455 6.340 6.184 5.811 5.378 5.176
T ) 423 K 0.379 40.9 0.738 51.0 1.230 58.6 2.496 58.4 3.855 62.4 4.627 64.9
15.290 16.708 17.580 17.675 18.494
7.286 7.234 7.131 7.010 6.872 6.783 6.710 6.495 6.311 6.123 6.001
Figure 2. Concentration of methane as a function of pressure in the gas and liquid coexisting phases for the mixture tetralin + methane at four temperatures (9, 294 K; 4, 323 K; b, 373 K; 0, 423 K).
liquid phase
C1/(mol‚L-1)
C2/(mol‚L-1)
C1/(mol‚L-1)
C2/(mol‚L-1)
0.504 0.634 0.786 0.984 1.213 1.511 1.807 2.248 2.192 2.180 2.391 2.413
18.951 19.220 19.309 19.275 19.010 18.635 17.988 17.114 17.016 17.017 16.555 16.484
5.649 5.405 5.186 4.937 4.676 4.269 3.973 3.565 3.553
6.218 7.230 7.986 8.875 9.803 11.122 12.057 13.503 13.266
3.373 3.277
13.850 14.058
0.563
17.110
0.810
17.465
1.132
17.496
1.672 2.143 2.400
16.745 15.780 15.060
5.248 5.251 5.241 4.876 4.951 4.497 4.683 3.903 3.700 3.634 3.580
6.946 6.907 7.015 7.891 7.957 9.220 8.868 11.096 11.874 12.023 12.169
0.454 0.748 0.896 1.171 1.761
13.120 13.947 14.481 14.274 13.610
5.036 4.584 4.320 4.019 3.732 2.859
5.969 7.367 8.096 8.861 9.631 11.734
0.417 0.696 1.526 1.513 2.022 2.514
10.324 11.988 11.793 11.848 11.450 10.699
5.001 4.301 3.686
4.909 6.963 8.352
3.620 3.041
8.804 9.939
Figure 3. Phase diagrams of tetralin + methane at four temperatures (9, 294 K; 4, 323 K; b, 373 K; 0, 423 K). x, y ) C2/(C1 + C2) ) mole fractions of methane.
Journal of Chemical and Engineering Data, Vol. 44, No. 6, 1999 1209 Table 2. Vapor-Liquid Equilibrium Data for 9,10-Dihydrophenanthrene + Methane at (423 and 463) K (C1 ) 9,10-Dihydrophenanthrene Concentration; C2 ) Methane Concentration) gas phase
liquid phase
P/MPa C1/(mol‚L-1) C2/(mol‚L-1) C1/(mol‚L-1) C2/(mol‚L-1) T ) 423 K
Figure 4. Phase diagram of tetralin + methane (0, this work, 423 K; b, Sebastian et al. (1979), 461.7. x, y ) C2/(C1 + C2) ) mole fractions of methane.
6.3 10.4 16.2 22.4 30.4 40.8 51.1 61.3 71.5 81.4 91.6 101.9 112.7 121.6 131.3 141.2 151.5 158.7 161.2 161.8
uncertainty on the mole fraction may be computed by
∆c ∆y ) 2 (1 - y) y c
(1)
where ∆c/c is the relative uncertainty for concentration measurements. As a result, ∆y/y is always lower or equal to 2∆c/c even if the concentration of the minor component goes to zero. Here again the most important source of uncertainty is the pressure gauge with an accuracy of 0.4 MPa. Results Methane + Tetralin Mixture. Vapor-liquid equilibrium data for the methane + tetralin mixture are reported in Table 1. Tetralin (C1) and methane (C2) concentrations
6.347 8.363 10.425 12.127 13.460 14.545 15.318 15.991 16.648 16.842 16.842 17.111 16.878 16.492 15.852
1.784
15.078
0.372 0.653 0.995 1.386 1.932 2.616 3.161 3.801 4.503 4.933 5.576 6.351 6.978 7.709 8.343 9.196 10.357 11.937 12.127 12.563
5.242 5.202 5.145 5.078 4.944 4.874 4.738 4.579 4.439 4.356 4.087 3.976 3.825 3.748 3.606 3.417 3.424
0.123 0.372 0.705 1.104 1.616 2.204 2.838 3.516 4.168 4.808 5.742 6.063 6.783 6.917 7.575 8.189 8.029
3.449 3.284 3.253 2.984
8.302 8.666 8.658 9.609
T ) 463 K 2.2 6.2 11.0 16.5 24.2 31.4 41.6 51.9 61.6 70.9 81.1 86.6 94.8 99.8 104.6 108.8 110.4 111.7 112.9 113.9 114.9 116.5
Figure 5. Concentration of 9,10-dihydrophenanthrene as a function of pressure in the gas and liquid coexisting phases for the mixture 9,10-dihydrophenanthrene + methane at (b) 423 K and (2) 463 K.
0.053 0.068 0.092 0.117 0.153 0.200 0.257 0.346 0.489 0.494 0.745 0.787 0.970 1.243 1.553
5.365 5.320 5.231 5.169 5.057 4.935 4.779 4.690 4.427 4.394 4.268 4.036 3.941 3.773 3.617 3.410 3.136 2.705 2.650 2.554
0.094 0.164 0.242 0.406 0.511 0.670
11.305 12.469 13.363 14.148 14.414 14.591
0.832 1.028 1.025 1.171 1.089
14.856 14.571 14.342 14.474 14.454
1.345
14.233
in each phase are given at various pressures. Other quantities such as mole fraction and molar volume may be determined from these data. Figures 1 and 2 show plots of tetralin and methane concentrations as a function of pressure along the coexistence lines. Pressure-mole fraction plots at (294, 323, 373, and 423) K including the critical vicinity are shown in Figure 3. Notice that, in this temperature range, the mixture critical pressure decreases with increasing temperature. This may be discussed in view of the classical classification of phase diagrams for binary mixtures (Van Konynenburg and Scott, 1980). In all types of phase diagrams except for type III the critical line exhibits a maximum in pressure and decreases toward the critical point of the heavier component. Such a maximum in pressure, if it exists, is expected to lie at a lower temperature. It is a common feature of these diagrams that the maximum in pressure is found at temperatures closer to the light component critical temperature (here 190 K) than to the heavier one (here 716 K). Figure 4 shows a comparison of our data at 423 K with those reported by Sebastian et al. (1979) at 461 K. Though at different temperatures, the data may be compared because, as may be seen in Figure 3, the data at
1210
Journal of Chemical and Engineering Data, Vol. 44, No. 6, 1999
Figure 6. Concentration of methane as a function of pressure in the gas and liquid coexisting phases for the mixture 9,10dihydrophenanthrene + methane at (b) 423 K and (2) 463 K.
Figure 8. Comparison of gas-phase mole fractions of the mixture 9,10-dihydrophenanthrene + methane at 463 K (2, this work; 0, Sebastian et al. (1980)) on an appropriate scale. y ) C2/(C1 + C2) ) mole fraction of methane.
reported at lower pressures by Sebastian et al. (1980). Although it was possible to determine whole phase envelopes, the measurements near the critical points were more difficult. Again, the critical pressure decreases with increasing temperature though the temperature range is far from the 9,10-dihydrophenanthrene critical temperature (774 K). Both mixtures seem to have a similar behavior regarding this question and the same comment as above applies. Conclusion We have determined phase diagrams of the mixtures methane + tetralin and methane + 9,10 -dihydrophenanthrene at various temperatures. Other measurements on light + heavy hydrocarbon systems are in progress and will be published later. List of Symbols Figure 7. Phase diagram of 9,10-dihydrophenanthrene + methane at two temperatures (b) 423 K and (2) 463 K, this work; and (0) 463 K, Sebastian et al. (1980). x, y ) C2/(C1 + C2) ) mole fractions of methane.
low pressure (below about 25 MPa) on the bubble curve lie nearly on the same line for different temperatures and diverge only at high pressure. Figure 4 shows that our data at 423 K are consistent with those reported by Sebastian et al. (1979). Methane + 9,10-Dihydrophenanthrene Mixture. 9,10-Dihydrophenanthrene (C1) and methane (C2) concentrations for this mixture at 423 and 463 K are reported in Table 2. Variations of 9,10-dihydrophenanthrene and methane concentrations with pressure are shown in Figures 5 and 6. Data for the gas phase at low pressures were not measurable for the same reason as above. The phase envelopes are shown in Figure 7. The agreement with the data of Sebastian et al. (1980) at 463 K in the liquid phase is good. As for the gas phase, it can be seen in Figure 8 that our data at high pressure are consistent with those
C1 ) concentration of the heavy component (tetralin or 9,10-dihydrophenanthrene) C2 ) concentration of methane P ) pressure, MPa T ) temperature, K x ) mole fraction of methane in the liquid phase y ) mole fraction of methane in the gas phase Literature Cited Marteau, P.; Tobaly, P.; Ruffier-Meray, V.; Barreau, A. In Situ Determination of High Pressure Phase Diagrams of Methane-Heavy Hydrocarbon Mixtures Using an Infrared Absorption Method. Fluid Phase Equilib. 1996, 119, 213-230. Marteau P.; Obriot, J.; Ruffier-Meray, V.; Behar, E. Experimental Determination of Phase Behavior of Binary Mixtures: MethaneHexane and Methane-Benzene. Fluid Phase Equilib. 1997, 129, 285-305. Marteau, P.; Tobaly, P.; Ruffier-Meray, V.; de Hemptinne, J. C. High Pressure Phase Diagrams of Methane + Squalane and Methane + Hexatriacontane Mixtures. J. Chem. Eng. Data 1998, 43, 362-366.
Journal of Chemical and Engineering Data, Vol. 44, No. 6, 1999 1211 Sebastian, H. M.; Simnick, J. J.; Lin H.; Chao K. Gas-Liquid Equilibrium in Binary Mixtures of Methane with Tetralin, Diphenylmethane, and 1-Methylnaphthalene. J. Chem. Eng. Data 1979, 24, 149-152. Sebastian, H. M.; Lin H.; Chao K. Gas-Liquid Equilibrium in Mixtures of Methane plus 9,10-Dihydrophenanthrene at Elevated Temperatures and Pressures. J. Chem. Eng. Data 1980, 25, 379-381.
Van Konynenburg, P. H.; Scott R. L. Critical Lines and Phase Equilibria in Binary van der Waals Mixtures Philos. Trans. R. Soc. London 1980, 298, 495-540. Received for review February 9, 1999. Accepted July 8, 1999.
JE990045J
